This invention relates to a linkage useful, for example on a musical instrument stand, wherein a small-diameter pipe is inserted into a large-diameter pipe and the pipes are to be linked and maintained in such a fashion as to be freely capable of expansion and contraction of the linked pipes.
In a known cymbal stand 50 shown in FIG. 5, for example, cymbals are supported at the top of a series of pipes. The pipes are ordinarily made of metal. They include an upper pipe 54, a middle pipe 53 and a lower pipe 52. The pipes are connected and held to be freely capable of elongation and contraction by each smaller diameter pipe being inserted into a larger-diameter pipe like the smaller middle pipe 53 in the larger bottom pipe 52, and the smallest upper pipe 54 in the smaller middle pipe 53.
A known linking connection between two of these pipes is shown in cross section in FIG. 6. It comprises a pipe linkage device 60 comprising a tightening bush 61 for holding, a main body 66 for holding and a tightening member 70. The tightening bush 61 is a tubular body, which is C-shape in transverse cross-section, including a cut (not shown). A small-diameter pipe 54 (or 53) is inserted into and held by the bush 61.
On one axial side, the main holding body 66 has a large-diameter tubular pipe insertion sleeve 67 for holding the outer periphery of the terminal part of the large-diameter pipe 53 (or 52). The other axial side of the body 66 includes a tubular tightening bush storage receptacle 68 for accommodating the tightening bush 61 enabling the small-diameter pipe 54 that has been inserted into and is held by the tightening bush 61 to run through the tightening bush storage part 68.
In this pipe linkage and holding device 60, the main holding body 66 is fitted to the outer periphery at the terminal end of the large-diameter pipe 53 and the tightening bush 61. The small-diameter pipe 54 runs through the bush 61 and is accommodated into the tightening bush storage receptacle 68 of the main holding body 66, resulting in one end of the small-diameter pipe 54 being inserted into the large-diameter pipe 53. When the tightening member 70 is thereafter tightened from outside of the main holding body 66, the small-diameter pipe 54 is in place.
When using such a linkage structure of the pipes, however, during a musical performance wherein cymbals 51 or tom-toms, etc. are installed above the cymbal stand 50 and are beaten violently, the free terminal part 54a on the linkage side of the small-diameter pipe 54 inside the large-diameter pipe 53 both rotates and shifts due to the vibrations, with the rotation having the linkage holding device 60 as its center. This causes a contact of the terminal part 54a with the inside of the large-diameter pipe 53, thereby producing unnecessary noise due to contact between the pipes.
To avoid such an inconvenience, it is possible to avoid the contact between the small-diameter pipe 54 in the large-diameter pipe 53 by increasing the diameter difference between the large-diameter pipe 53 and the small-diameter pipe 54. In this kind of stand construction, however, there are limits to the diameters of the pipes that are selected. If the large-diameter pipe 53 is used as the standard, the small-diameter pipe 54 becomes small in size,.thereby making it look or be weak. If the small-diameter pipe 54 is used as the standard, on the other hand, the diameter of the large-diameter pipe 53 becomes larger, causing the outside appearance to become less appealing. In addition, an added problem develops in that the overall weight of the stand 50 becomes greater. Accordingly, it would be more desirable for the outside appearance if the difference in diameter between the large-diameter pipe 53 and the small-diameter pipe 54 is small.
An object of the invention is to provide a pipe linkage arrangement, by which a small-diameter pipe and a large-diameter pipe may be connected and held more firmly by using a simple structure, the pipes themselves being linked and held without shakiness, and undesired noise being effectively prevented during the performance.
The invention concerns a pipe linkage useful, for example, for a musical stand. The linkage comprises a bush installed at a terminal end on the linking side of a small-diameter pipe which is to be inserted into the inner tube of a large-diameter pipe. The bush is linked and maintained so as to be expanded or permitted to contract by a linkage holding device. The bush comprises a main body having an outer peripheral surface that can be inserted into the inner tube of the connected part of the small-diameter pipe. The bush has a large-diameter collar or part with an outer peripheral surface that can be inserted into the inner tube of the large-diameter pipe through a step which touches the edge of the terminal part on the linkage side of the small-diameter pipe. A bolt insertion hole that runs through the main body and the large-diameter collar receives a tightening bolt. A nut fixing receptacle on the terminal side of the main body of the bolt insertion hole receives a tightening nut for the bolt. A bolt installation seat for the tightening bolt is defined on the side terminal face of the large-diameter part of the insertion hole. As the tightening bolt is passed through the bolt insertion hole and is tightened into the tightening nut, the outer peripheral surface of the main bush body is compressively swollen while the bush may be installed inside the small-diameter pipe. At the same time, the contact of the small-diameter pipe with the interior of the large-diameter pipe is mitigated by the outer-peripheral surface of the large-diameter collar or part of the bush.
Often objects and features of the invention are explained below with reference to the attached drawings.